[stump4545]

is it time to change my recitfer tube on my preamp for sure?

[Steve]

is it time to change my recitfer tube on my preamp for sure?

Purple is definitely yes. Blue, if around the materials maybe due to cobalt impurities and no problem. I would assume the rectifier is new.

Cheers.

[Wayner]

I  believe the color is also from impurities in the plasma stream within the tube. I had an old Dynaco Stereo 70 amp that exhibited glowing blue tubes near end of life. I'd keep running it until I get other signs of tube failure.

Wayner

[stump4545]

should i ever be concerned that the rectifier blows up! or does anything dangerous?

thanks for the help.

[Quiet Earth]

Which rectifier are you using? (what number designation, like 6X5, or 5u4?)

Is the blue glow only on the inside of the glass, like a blue frost? Or is it a bright blue light comming from within the tube?

How long has it been since you replaced the rectifier?

[stump4545]

i was using a  mullard F32B1D1 that i have had for about 2 years so i think it is about time to change but wasn't sure if the blue neon light is a normal warning to change.

thanks a lot.

[Quiet Earth]

Sorry for the late reply. Is that number actually the rectifier part number or is it a Mullard date code? Just curious . . . .

If it were me I would probably get a new rectifier anyway just see if there is a change/difference/improvement. If there is no change then you have a spare tube,,, which is always a good thing. 

[ltr317]

F32 is the type of tube.  I don't have the Mullard list so not sure which type of rectifier.  B1D1 = Blackburn factory, 1961 or 1971, manufactured in the first week of April.